Inspection device for filter cigarettes

ABSTRACT

An inspection device for filter cigarettes has a blocking pad ( 60 ) and a suction pad ( 80 ) for holding a filer cigarette (FC) therebetween at an inspection position when the filter cigarette (FC) is transferred along a transfer path in a filter-attaching machine, a pressure detector ( 94 ) for detecting the magnitude of the negative pressure produced in the filter cigarette (FC) when air in the filter cigarette (FC) is sucked in through the suction pad ( 80 ) in the state where the filter cigarette (FC) is held between the blocking pad ( 60 ) and the suction pad ( 80 ), and a controller ( 108 ) for deciding whether there is an adhesion defect of tip paper of the filter cigarette (FC) or not, based on the output from the pressure detector ( 94 ).

TECHNICAL FIELD

The present invention relates to a device for inspecting whether filter cigarettes are defectives or not, and more specifically to a device for detecting whether there is the possibility that a filter plug comes off a filter cigarette or not.

BACKGROUND ART

A filter-attaching machine makes filter cigarettes, and a filter cigarette has a cigarette and a filter plug connected to one end of the cigarette by wrapping tip paper.

In such a filter cigarette, the unsatisfactory application of glue to the tip paper entails incomplete adhesion between the tip paper and the cigarette. As a result, there is fear that the filter plug drops off the cigarette along with the tip paper after the filter cigarette is produced. A cigarette, from which the filter plug is lacked, is a so-called headless cigarette.

In general, the filter-attaching machine includes an inspection device for inspecting manufactured filter cigarettes for defects. The inspection device, however, is not capable of detecting the possibility that a filter cigarette will become a headless cigarette.

More specifically, a well-known inspection device first injects air into a filter cigarette to raise the inner pressure of the filter cigarette. In this state, the device then measures the amount of air leakage from the filter cigarette and based on the measured amount of leakage, detects a hole and a break that exist in the wrapping material of the cigarette and in the tip paper.

Consequently, according to the above-mentioned inspection device, if there exists a gap between the tip paper and the cigarette due to an adhesion defect of tip paper, the gap is closed as the inner pressure of the filter cigarette is increased at the time of inspection, which makes it impossible to detect the presence of the gap, namely the possibility that the filter cigarette will become a headless cigarette.

An object of the present invention is to provide an inspection device for filter cigarettes, which is capable of surely and appropriately detecting an adhesion defect of tip paper in the manufacturing process of filter cigarettes.

DISCLOSURE OF THE INVENTION

The above object is accomplished by an inspection device for filter cigarettes according to the present invention. A filter cigarette has a cigarette, a filter plug, and tip paper for connecting the cigarette and the filter plug to each other. The inspection device of the present invention comprises a transfer path for transferring a filter cigarette in a state where an edge of the tip paper, which is located on the side of the cigarette, is exposed over the whole circumference thereof; a suction pad and a blocking pad adapted to come into tight contact with a mouthpiece end and a cigarette end of the filter cigarette, respectively, for holding the filter cigarette therebetween when the filter cigarette reaches an inspection position defined in the transfer path; a suction circuit for sucking air from the filter cigarette held between the suction pad and the blocking pad through a suction path connected to the suction pad at the inspection position; a detector for measuring pressure in the filter cigarette and outputs a measurement result when the air in the filter cigarette is sucked in; and a decision device for deciding whether there is produced a gap between the cigarette and the tip paper or not, based on the measurement result from the detector.

If adhesion of the tip paper is incomplete, there exists a gap between the cigarette and the tip paper. In such a case, when the air in the filter cigarette is sucked in at the inspection position, the suction contracts an external diameter of the cigarette and expands the gap. As a result, outside air is introduced through the enlarged gap into the filter cigarette, so that the pressure in the filter cigarette does not fall on a large scale. On the contrary, if there is no gap attributable to an adhesion defect of the tip paper, the pressure in the filter cigarette is drastically decreased.

Consequently, it is accurately decided whether there is a gap in the filter cigarette or not, that is, whether there is an adhesion defect of tip paper or not, based on the pressure in the filter cigarette measured by the detector. This makes it possible to detect the possibility that the filter cigarette will become a headless cigarette.

More specifically, the detector is capable of measuring differential pressure between negative pressure in the suction path and reference negative pressure as the pressure in the filter cigarette.

Furthermore, the transfer path includes a rotatable inspection drum, which has a plurality of receiving grooves that are arranged in an outer circumferential surface thereof at regular intervals in the circumferential direction and receive filter cigarettes individually. In this case, the inspection position is defined by a given rotation angle position, as viewed in a rotating direction of the inspection drum.

The transfer path of the filter-attaching machine generally includes a drum train formed by arranging a plurality of grooved drums, one right next to the other. Therefore, if one grooved drum among the drum train is replaced as the inspection drum, the inspection device can be smoothly installed in the filter-attaching machine.

In a case that the tip paper of the filter cigarette has a perforation area that introduces air into the filter plug, the suction circuit includes closure means for closing the perforation area of the tip paper at the inspection position.

Specifically, the closure means includes a rotatable shutoff roller located so as to come into rolling contact with the inspection drum at the inspection position. The shutoff roller has a plurality of shutoff grooves arranged in an outer circumferential surface thereof at regular intervals in the circumferential direction. The shutoff grooves closes the perforation area of the tip paper in cooperation with the receiving groove of the inspection drum.

When air in the filter cigarette is sucked in, the perforation area of the tip paper is closed, so that the outside air is not introduced into the filter cigarette through the perforation area. Consequently, based on the pressure in the filter cigarette which is measured by the detector, it is decided with accuracy whether there is an adhesion defect of the tip paper, that is to say the presence of a gap or not.

Furthermore, it is preferable that the cigarette be partially or entirely covered with cover means at the time of inspection. To be concrete, the cover means includes a rotatable cover roller located so as to come into rolling contact with the inspection drum at the inspection position. The cover roller has a plurality of cover grooves arranged in an outer circumferential surface thereof at regular intervals in the circumferential direction. The cover groove partially or entirely covers the cigarette in cooperation with the receiving groove of the inspection drum.

When the inspection is carried out, the cover means, namely the cover roller, reduces or shuts off the outside air that flows into the filter cigarette through the wrapping material of the cigarette. For this reason, the inspection accuracy is not adversely affected by such outside air inflow.

Moreover, the inspection device further includes a movable carrier that is provided to the inspection drum and reciprocates the blocking pad in directions moving toward and away from the suction pad. The movable carrier moves toward the suction pad with the blocking pad, to thereby cause the blocking pad and the suction pad to hold the filter cigarette therebetween.

In that case, the suction pad is fixed with respect to an axial direction of the filter cigarette, so that the volume of the suction path extending from the suction pad is constant, which contributes greatly to an improvement in inspection accuracy.

The movable carrier may include a cigarette holder having a receiving groove. In this case, when the blocking pad is moved toward the suction pad, the filter cigarette moves along with the cigarette holder. Therefore, the filter cigarette does not come into sliding contact with the receiving groove.

Additionally, the inspection device may further include separating means for forcibly separating the blocking pad from the cigarette end of the filter cigarette after the filter cigarette passes the inspection position. Specifically, the separating means includes a rod coupled to the blocking pad, a spring for urging the rod toward the suction pad, and a cam mechanism for moving the rod in such a direction that the blocking pad withdraws from the suction pad against the urging force of the spring.

After the inspection, even if the blocking pad is in tight contact with the cigarette end, the separating means forcibly separates the blocking pad from the cigarette end, so that the blocking pad does not interfere with the transfer of the filter cigarette.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a part of a transfer path for filter cigarettes, which passes through an inspection device in a filter-attaching machine;

FIG. 2 is a longitudinal section of an inspection drum of FIG. 1;

FIG. 3 is a view showing a suction path extending from a suction pad to a suction pump;

FIG. 4 is a view showing a state immediately after a filter cigarette is received by the inspection drum;

FIG. 5 is a view showing a state where a filter cigarette is held between a blocking pad and the suction pad after the filter cigarette is received by the inspection drum;

FIG. 6 is a view showing a state of a filter cigarette located in an inspection position on the inspection drum;

FIG. 7 is a schematic view for explaining functions of a shutoff roller and a cover roller; and

FIG. 8 is a view showing a state of a filter cigarette after inspection.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 shows a part of a transfer path in a filter-attaching machine, and the transfer path transfers manufactured filter cigarettes.

The transfer path shown in FIG. 1 is defined by a drum train 2. The drum train 2 includes three grooved drums, namely transfer drums 4, 6 and 8. The transfer drums are arranged one right next to the other, and two adjacent transfer drums are rotated in directions opposite to each other. When a filter cigarettes is supplied to a groove of the transfer drum 4 located upstream in the drum train 2, the filter cigarette is transferred to the adjacent transfer drum in order while the transfer drums rotate.

The transfer drum 6 located in the middle of the drum train 2 is an inspection drum which is associated with a shutoff roller 10 and a cover roller 12.

As illustrated in FIG. 2, the inspection drum 6 has a rotary shaft 14 at the center thereof, and the rotary shaft 14 is enclosed by a fixed sleeve 16. Both end-portions of the rotary shaft 14 are rotatably supported by the fixed sleeve 16 through respective bearings 17. The fixed sleeve 16 has a flange 18 at one end portion thereof, and the flange 18 is fixed to a frame 22 of the device with a plurality of setscrews 20.

The rotary shaft 14 has one end protruding from the one end of the fixed sleeve 16 on a back surface side of the frame 22. A drive gear 24 is mounted on the one end of the rotary shaft 14. Once a driving force is transmitted to the drive gear 24, the rotary shaft 14 rotates with the drive gear 24 in one direction.

The fixed sleeve 16 is enclosed by a cam sleeve 26, and the cam sleeve 26 is fixed to the fixed sleeve 16.

The other end of the rotary shaft 14 projects from the other end of the fixed sleeve 16, and a cylindrical rotor 28 is coupled to the other end of the rotary shaft 14 through a flange of the shaft 14. A part of an outer circumferential surface of the rotor 28 and that of the cam sleeve 26 form a cylindrical seat surface 29 in cooperation with each other. There is mounted a hollow-cylindrical rotating shell 30 on the cylindrical seat surface 29. A step, or a flange, is formed on each side of the cylindrical seat surface 29. The flanges restrict the rotating shell 30 in movement in an axial direction thereof.

The rotating shell 30 is coupled to the rotor 28 through a coupling disc 31. Therefore, rotational power of the rotary shaft 14 is transmitted from the rotor 28 to the rotating shell 30, whereby the rotating shell 30 is rotated with the rotary shaft 14. At this time, the rotating shell 30 rotates integrally with a portion of the cylindrical seat surface 29 of the rotor side while being in sliding contact with the cylindrical bearing surface 29 of the cam sleeve side.

The rotating shell 30 has a plurality of slots 32, which are arranged at regular intervals in a circumferential direction of the rotating shell 30. Accordingly, the outer circumferential surface of the cam sleeve 26 is partially exposed through the slots 32.

Furthermore, guide rods 36 are located in the respective slots 32 of the rotating shell 30 and extend in the axial direction of the rotating shell 30. Sliders 34 are slidably mounted on the respective guide rods 36 of the slots 32. Each of the sliders 34 can reciprocate in the slot 32 in the axial direction of the rotating shell 30, namely along the guide rod 36.

There is formed a cam groove 38 in the cylindrical seat surface 29, or in the outer circumferential surface of the cam sleeve 26. The cam groove 38 extends over the whole circumference of the cam sleeve 26. A cam follower 40 provided to each of the sliders 34 is interfitted in the cam groove 38. More specifically, each of the sliders 34 has a roller shaft, which protrudes from the slider 34 toward the rotating shell 30. A roller or the cam follower 40 is rotatably mounted on a distal end of the roller shaft. The rotation of the rotating shell 30 transfers the sliders 34 in the circumferential direction of the cam sleeve 26. Simultaneously, the cam followers 40 of the sliders 34 are guided along the cam groove 38, and the sliders 34 are reciprocated in the axial direction of the rotating shell 30 in accordance with the profile of the cam groove 38.

Moreover, a movable carrier 42 is mounted on each of the sliders 34, the movable carrier 42 being formed into a stepped block. The right end portion of the carrier 42 is lower, as viewed in FIG. 1, and the left end portion thereof is higher than the right end portion.

A cigarette holder 43 is fitted to the right end portion of the movable carrier 42. The cigarette holder 43 has a pair of projections. The projections protrude outward in a radial direction of the rotating shell 30 and located away from each other with a given space therebetween in the axial direction of the rotating shell 30. Each of the projections is shaped into a U as viewed in a cross-section of the rotating shell 30, thereby having a groove 46 shaped like an arc.

A suction hole 48 is opened in the bottom of each groove 46. The suction holes 48 extend in the inside of the cigarette holder 43 to a bottom surface thereof. Each suction hole 48 has an inner end always communicated with a suction passage 50. The suction passage 50 extends through the movable carrier 42 and the slider 34 and is opened in a bottom surface of the slider 34 to communicate with the slot 32. The open end of the suction passage 50 is surrounded by a ring seal 52 which is fixed to the bottom surface of the slider 34. The ring seal 52 is accommodated in the slot 32 and is air-tightly in contact with the outer circumferential surface of the cam sleeve 26.

Furthermore, two control slots 54 are formed in the cam sleeve 26. The control slots 54 are located to be able to communicate with the suction passage 50, as viewed in the axial direction of the cam sleeve 26, and extend over respective given areas on the same circumference, as viewed in the circumferential direction of the cam sleeve 26.

The control slots 54 always communicate with an annular suction chamber 56. The suction chamber 56 is formed in between the cam sleeve 26 and the fixed sleeve 16. The suction chamber 56 is connected to an outside suction source through a suction path, and a given suction pressure is continuously supplied into the suction chamber 56. Functions of the control slots 54 will be clarified by the following explanation.

Once the rotating shell 30 is rotated, the movable carriers 42 are transferred with the sliders 34 in the circumferential direction of the cam sleeve 26. In this transfer process, when the movable carrier 42 and the suction passage 50 of the slider 34 reach the control slot 54, the suction passage 50 communicates with the control slot 54 through the ring seal 52. At this time, the suction pressure in the control slot 54 is supplied through the suction hole 48 to each groove 46 of the cigarette holder 43.

Referring to FIG. 2, the left end portion of the movable carrier 42 forms a protrusion 57 that projects outward in the radial direction of the rotating shell 30, compared to the right end portion. There is disposed a pad rod 58 in the protrusion 57, the pad rod 58 being aligned with the grooves 46 of the cigarette holder 43. With respect to the movable carrier 42, the pad rod 58 moves integrally with the movable carrier 42 in the rightward direction, as viewed in FIG. 2, and can move independently of the movable carrier 42 in the leftward direction due to a separating mechanism.

More specifically, the pad rod 58 has one end projecting from the protrusion 57 in the leftward direction. The other end of the pad rod 58 is attached with a blocking pad 60 that is elastically deformable. The blocking pad 60 projects from the protrusion 57 toward the cigarette holder 43. The blocking pad 60 is made of silicone resin and has a through-hole at the center thereof. The through-hole of the blocking pad 60 is closed by the other end of the pad rod 58.

A compression coil spring 62 is accommodated in the protrusion 57. The compression coil spring 62 surrounds the pad rod 58, to thereby urges the pad rod 58 in such a direction that the pad rod 58 protrudes from the protrusion 57.

A roller shaft 63 is attached to one end of the pad rod 58, and the roller shaft 63 extends outward in the radial direction of the rotating shell 30. A roller, namely a cam follower 64, is rotatably mounted on the end of the roller shaft 63.

Disposed near the cam follower 64 is a face cam 66. The face cam 66 is formed in the shape of an arc and surrounds the outside of the rotating shell 30. The face cam 66 is supported by the frame 22 through a stay 68.

A ring-shaped carrier 70 is attached to the outer circumferential surface of the rotating shell 30 to be on the side of rotor 28. The carrier 70 rotates integrally with the rotating shell 30. The carrier 70 has a plurality of plug holders 72 at one end portion thereof, the plug holders 72 being arranged at regular intervals in a circumferential direction of the carrier 70. More specifically, each of the plug holders 72 faces the corresponding cigarette holder 43 of the movable carrier 42, as viewed in the axial direction of the rotating shell 30, and has a groove 74 similar to the groove 46 of the cigarette holder 43. In other words, the grooves 46 and 74 are located on the same axis and function as one receiving groove 76 (see FIG. 1). The receiving groove 76 can receive one filter cigarette.

Moreover, the carrier 70 has a pad-mounting disc 78 at the other end portion thereof, and a plurality of suction pads 80 is fixed to one end face of the pad-mounting disc 78. The suction pads 80 are disposed at regular intervals in the circumferential direction of the rotating shell 30. That is to say, each of the suction pads 80 is positioned on the same axis as the corresponding blocking pad 60 to face the blocking pad 60. The suction pads 80 are made of silicone resin just like the blocking pads 60 and are elastically deformable. Each of the suction pads 80 has a through-hole at the center thereof. The through-hole is opened in the other end face of the pad-mounting disc 78, or the outer end face thereof, through a connecting hole in the pad-mounting disc 78.

The pad-mounting disc 78 is provided with a suction unit 81 in the outer end face thereof, and the suction unit 81 has a contact pad 82. The contact pad 82 is always pressed against the outer end face of the pad-mounting disc 78. More specifically, a support rod 84 extends from the contact pad 82 and is slidably supported by a bracket 86. There is disposed a compression coil spring 88 in between the bracket 86 and the contact pad 82. The compression coil spring 88 presses the contact pad 82 against the pad-mounting disc 78.

Furthermore, the contact pad 82 is located with respect to the pad-mounting disc 78 to communicate with the through-holes of the suction pads 80 one by one. In other words, when the suction pad 80 moves in the circumferential direction of the rotating shell 30 by the rotation of the rotating shell 30, the suction pads 80 sequentially pass the position of the contact pad 82. At this time, the through-hole of the suction pad 80 communicates with the inside of the contact pad 82 through the connecting hole in the pad-mounting disc 78. Specifically, the contact pad 82 is positioned on a circular track along which an open end of the connecting hole is moved. The position of the contact pad 82 defines the inspection position for filter cigarettes transferred on the inspection drum 6. The inspection position is in a given rotation angle position, as viewed in the rotating direction of the inspection drum 6.

When the suction pad 80 is connected to the contact pad 82 at the inspection position, the suction pad 80 is connected to the suction circuit through the contact pad 82. More specifically, a suction path 90 extends from an inner path of the contact pad 82 and is connected to a suction pump 92 and a semiconductor pressure converter 94.

As is obvious from FIG. 3, the suction path 90 branches off into two suction channels 90 a and 90 b. The suction channel 90 a is connected to the suction pump 92 through an orifice 96 and a pressure adjuster 98, and the suction channel 90 b to the pressure converter 94.

Connected to the pressure converter 94 is an outside air-introducing path 100, and an orifice 102 is interposed in the outside air-introducing path 100. Furthermore, an outside air-introducing channel 104 diverges from between the orifice 102 and the pressure converter 94 in the outside air-introducing path 100. The outside air-introducing channel 104 is connected to between the orifice 96 and the pressure adjuster 98 in the suction channel 90 a through an orifice 106.

Openings of the orifices 96, 102 and 106 are adjusted such that differential pressure between negative pressures applied to both sides of the pressure converter 94 become substantially zero when the suction pump 92 is driven in a state where the contact pad 82 is blocked up. The pressure converter 94 outputs a signal indicative of the differential pressure to a controller 108. The controller 108 includes a microcomputer, which has a decision circuit that executes the after-mentioned inspection on the basis of the signal from the pressure converter 94.

Referring to FIG. 2 again, there is disposed another rotary shaft 108 near the inspection drum 6, and the rotary shaft 108 extends in parallel with the rotary shaft 14 of the inspection drum 6. The rotary shaft 108 is also enclosed by a fixed sleeve 112, and both end portions of the shaft 108 are rotatably supported by the fixed sleeve 112 through a pair of bearings 110. The fixed sleeve 112 is coupled to the frame 22.

One end of the rotary shaft 108 projects from the fixed sleeve 112 on the back surface side of the frame 22, and a drive gear 114 is fitted to the one end of the rotary shaft 108. The drive gear 114 is engaged with the drive gear 24 of the inspection drum 6. Accordingly, when the rotary shaft 14 of the inspection drum 6 is rotated, the rotary shaft 108 is rotated in the direction opposite to the rotating direction of the rotary shaft 14.

The other end of the rotary shaft 108 protrudes from the fixed sleeve 112, and the shutoff roller 10 and the cover roller 12 are attached in tandem to the other end of the rotary shaft 108. More specifically, a common rotor 116 is coupled to the other end of the rotary shaft 108, and roller shells 118 and 120 are mounted on an outer circumferential surface of the rotor 116. The roller shells 118 and 120 cooperate with the rotor 116 to form the shutoff roller 10 and the cover roller 12, respectively. Consequently, the roller shells 118 and 120 rotate integrally with the rotary shaft 108.

The roller shells 118 and 120 have a plurality of shutoff grooves 122 and cover grooves 124, respectively, on respective outer circumferential surfaces. The shutoff grooves 122 and the cover grooves 124 are arranged at regular intervals in the circumferential directions of the corresponding roller shells. The shutoff grooves 122 and the cover grooves 124 are each formed into a shape similar to he receiving grooves 76 or the grooves 46 and 74.

When the rotating shell 30 of the inspection drum 6 and the roller shells 118 and 120 are rotated all together, the shutoff grooves 122 and the cover grooves 124 sequentially meet with the receiving grooves 76 (grooves 74 and 46) of the inspection drum 6 at the inspection position. In other words, the pitch and peripheral velocity of the receiving grooves 76 are set to be the same as the pitch and peripheral velocity of the shutoff grooves 122 and the cover grooves 124.

Functions of the inspection drum 6 associated with the shutoff roller 10 and the cover roller 12 will be explained below with reference to FIGS. 4 through 7 in addition to FIG. 1.

First, the inspection drum 6 receives filter cigarettes sequentially from the transfer drum 4 located upstream thereof into the receiving grooves 76. More specifically, as illustrated in FIG. 1, the transfer drum 4 has a suction area S₁ used for receiving and conveying filter cigarettes. The suction area S₁ extends up to a position right before a transfer position between the transfer drum 4 and the inspection drum 6, as viewed in the rotating direction of the transfer drum 4. The inspection drum 6 has a suction area S₂ extending from a position right before the transfer position, as viewed in the rotating direction thereof, and the suction area S₂ is formed by one of the control slots 54.

As a consequence, when a filter cigarette on the transfer drum 4 passes the transfer position, the receiving groove 76 (groove 46) of the inspection drum 6 enters the suction area S₂ to receive the supply of suction pressure from the control slot 54. The receiving groove 76 sucks the filter cigarette on the transfer drum 4 and receives the filter cigarette FC as shown in FIG. 4. The filter cigarette FC received is located between the blocking pad 60 and the suction pad 80.

In a case that the perforation area, for example one perforation line V, is formed in the tip paper of the filter cigarette FC, the perforation line V is positioned in the groove 74 (receiving groove 76) of the plug holder 72. The edge E of the tip paper on the side of the cigarette is located between the cigarette holder 43 and the plug holder 72, and is always exposed to the outside air over the whole circumference of the filter cigarette FC. In this case, the filter cigarette FC in the receiving groove 76 is in a state where the cigarette thereof is sucked by the two grooves 46.

Thereafter, the filter cigarette FC in the receiving groove 76 is transferred in the circumferential direction of the inspection drum 6 while the inspection drum 6 rotates. In the transfer process, the cam groove 38 of the cam sleeve 26 and the cam follower 40 cooperate with each other to move the cigarette holder 43 toward the suction pad 80 through the slider 34 and the movable carrier 42. This causes the filter cigarette FC to move with the cigarette holder 43 without sliding against the receiving groove 76, and a filter end or a mouthpiece end of the filter cigarette FC is brought into contact with the suction pad 80.

Immediately before the filter cigarette FC contacts the suction pad 80, the receiving groove 76 passes through the suction area S₂ (see FIG. 1), and the supply of suction pressure to the receiving grooves 76 (grooves 46) is temporarily suspended. At this time, the grooves 46 may be opened to the atmosphere.

After the filter cigarette FC contacts the suction pad 80, the cigarette holder 43, namely the movable carrier 42, continues to be moved while the cigarette holder 43 slides against the filter cigarette FC. Therefore, the blocking pad 60 moves toward the filter cigarette FC to come into contact with the end of the cigarette as shown in FIG. 5. As a result, the filter cigarette FC is held between the blocking pad 60 and the suction pad 80.

Subsequently, the receiving groove 76 enters the suction area S₃ (the other control slot 54). The grooves 46 (receiving groove 76) of the cigarette holder 43 is supplied again with the suction pressure from the control slot 54, so that the filter cigarette FC is sucked and held by the receiving groove 76.

When the supply of the suction pressure to the grooves 46 of the cigarette holder 43 is temporarily suspended, or when the grooves 46 is opened to the atmosphere, the filter cigarette FC does not fall off the receiving groove 76. The reason is that as illustrated in FIG. 1, a guide 126 is disposed outside the inspection drum 6 and extends from the suction area S₂ to the suction area S₃, to thereby prevent the filter cigarette FC from falling off the inspection drum 6.

Furthermore, when the filter cigarette FC is moved toward the suction pad 80, the edge of the tip paper does not enter the groove 74 of the plug holder 72.

Thereafter, the filter cigarette FC travels toward the shutoff roller 10 and the cover roller 12 while being held between the blocking pad 60 and the suction pad 80. When the filter cigarette FC passes the shutoff roller 10 and the cover roller 12, that is to say when passing the inspection position, as illustrated in FIG. 6, the shutoff groove 122 of the shutoff roller 10 (roller shell 118) cooperates with the groove 74 of the plug holder 72 to completely close the perforation line V of the filter cigarette FC. Simultaneously, the cover groove 124 of the cover roller 12 (roller shell 120) partially covers the cigarette of the filter cigarette FC in cooperation with the groove 46 of the cigarette holder 43.

At this time, since the suction pad 80 is connected to the suction pump 92 through the contact pad 82 as shown in FIG. 6, air in the filter cigarette FC is discharged by the suction pump 92 through the suction path 90. As a consequence, the pressure converter 94 detects differential pressure generated between the negative pressure in the suction channel 90 b and the negative pressure in the outside air-introducing channel 104 and outputs a signal indicative of the differential pressure to the controller 108.

The controller 108 decides whether the differential pressure is equal to or above a given criterion threshold value, based on the signal supplied from the pressure converter 94. If the differential pressure is equal to or above the criterion threshold value, the controller 108 decides that there generates an adhesion defect of the tip paper of the filter cigarette FC, or that there is the possibility that the filter cigarette FC will become a headless cigarette. When this happens, the controller 108 outputs a removal signal with respect to the filter cigarette FC. On the contrary, when the differential pressure is smaller than the criterion threshold value, the controller 108 decides that the filter cigarette FC is a non-defective product, or that there is no possibility that the filter cigarette FC will become a headless cigarette.

The above-mentioned decision principle will be described in detail. When the filter cigarette FC passes the inspection position, the cigarette end of the filter cigarette FC is closes by the blocking pad 60, whereas the mouthpiece of the filter cigarette FC is connected to with the suction pad 80. As is apparent from FIG. 7, the perforation line V of the tip paper of the filter cigarette FC is in a closed state because of the groove 74 of the plug holder 72 and the shutoff groove 122 of the shutoff roller 10.

When the air in the filter cigarette FC, which is a non-defective product, is discharged through the suction pad 80 in the above state, air is not introduced from the outside into the filter cigarette FC, and the pressure converter 94 does not detect a differential pressure equal to or above the criterion threshold value.

If the adhesion of the tip paper of the filter cigarette FC is incomplete, there is produced a gap between the tip paper and the cigarette due to the adhesion defect. In this case, when air is discharged from the filter cigarette FC and the inner pressure of the cigarette becomes negative pressure, the gap is enlarged due to the negative pressure. The gap thus widened introduces a large quantity of outside air into the filter cigarette FC, so that the pressure converter 94 detects a differential pressure equal to or above the criterion threshold value. As a result, the controller 108 detects the adhesion defect of the tip paper without fail, based on the signal from the pressure converter 94.

During the inspection, the cover groove 124 of the cover roller 12 cooperate with the grooves 46 of the cigarette holder 43 to partially cover the cigarette of the filter cigarette FC. Therefore, even if the wrapping material of the cigarette has air permeability in some measure, the cover roller 12 reduces the outside air introduced through the wrapping material into the filter cigarette FC. This enables the pressure converter 94 to detect the differential pressure attributable to the gap with high accuracy.

Since the suction pad 80 is not moved in the axial direction of the inspection drum 6, there occurs no fluctuation in volume of the suction path extending from each of the suction pads 80 to the suction pump 92, which greatly contributes to the improvement of the inspection accuracy.

Subsequently, the filter cigarette FC is conveyed on the inspection drum 6 toward the transfer drum 8 located downstream. In this conveying process, the cam groove 38 and the cam follower 40 cooperate with each other to move back the filter cigarette FC with the cigarette holder 43 in a direction withdrawing from the suction pad 80.

Immediately before the filter cigarette FC reaches the transfer drum 8, the blocking pad 60 is forcibly separated away from the cigarette end of the filter cigarette FC. That is to say, the cam follower 64 (see FIG. 2) of the blocking pad 60 is engaged with the cam face of the face cam 66, and the face cam 66 causes the pad rod 58 of the blocking pad 60 to be pulled against the urging force of the compression coil spring 62 through the cam follower 64. For this reason, even if the blocking pad 60 is in tight contact with the cigarette so as to bite thereinto, the blocking pad 60 is surely separated from the cigarette end as illustrated in FIG. 8.

As a consequence, the filter cigarette FC can be stably transferred from the inspection drum 6 to the transfer drum 8 located downstream thereof without interfering with the blocking pad 60. The blocking pad 60 subsequently returns to the position shown in FIG by the urging force of the compression coil spring 62. Reference character S₄ in FIG. 1 represents a suction area of the transfer drum 8.

The present invention is not limited to the above-described embodiment, and may be modified in various ways.

For instance, in a case that there is no perforation line formed in the tip paper of the filter cigarette FC, the shutoff roller 10 may be omitted.

At the time of inspection, moreover, the grooves 46 of the cigarette holder 43 and the grooves 124 of the cover roller 12 may cover the entire cigarette of the filter cigarette FC.

Furthermore, the specific material and shape of the blocking pad 60 and the suction pad 80 may be diversely altered. 

1. An inspection device for filter cigarettes each having a cigarette, a filter plug, and tip paper for connecting the cigarette and the filter plug to each other, said inspection device comprising: a transfer path that transfers said filter cigarette in a state where an edge of said tip paper on the cigarette side is exposed over the whole circumstance of the edge; a suction pad and a blocking pad adapted to come into tight contact with a mouthpiece end and a cigarette end of the filter cigarette, respectively, for holding the filter cigarette therebetween when the filter cigarette reaches an inspection position defined by said transfer path; a suction circuit for sucking in air in the filter cigarette held between said suction pad and said blocking pad through a suction path connected to said suction pad at said inspection position; a detector for measuring pressure in the filter cigarette and outputs a measurement result when the air in the filter cigarette is sucked in; and a decision device for deciding whether there is produced a gap between the cigarette and the tip paper, based on the measurement result from said detector.
 2. The inspection device according to claim 1, wherein: said detector measures differential pressure between negative pressure in said suction path and reference negative pressure as pressure in the filter cigarette.
 3. The inspection device according to claim 2, wherein: said transfer path includes a rotatable inspection drum, said inspection drum having a plurality of receiving grooves arranged in an outer circumferential surface thereof at regular intervals in the circumferential direction and receiving the respective filter cigarettes; and said inspection position is defined by a given rotation angle position, as viewed in a rotating direction of said inspection drum.
 4. The inspection device according to claim 3, wherein: the tip paper of the filter cigarette has a perforation area for introducing air into the filter plug; and said suction circuit includes closure means for closing the perforation area of the tip paper at said inspection position.
 5. The inspection device according to claim 4, wherein: said closure means includes a rotatable shutoff roller disposed so as to come into rolling contact with said inspection drum at said inspection position, and said shutoff roller has a plurality of shutoff grooves arranged in an outer circumferential surface thereof at regular intervals in the circumferential direction, said shutoff groove closing the perforation area of the tip paper in cooperation with said receiving groove of said inspection drum.
 6. The inspection device according to claim 5, wherein: said suction circuit further has cover means for partially or entirely covering the cigarette at said inspection position; and said cover means includes a rotatable cover roller disposed so as to come into rolling contact with said inspection drum at said inspection position, and said cover roller has a plurality of cover grooves arranged in an outer circumferential surface thereof at regular intervals in the circumferential direction, said cover groove partially or entirely covering the cigarette in cooperation with said receiving groove of said inspection drum.
 7. The inspection device according to claim 3, further comprising a movable carrier provided to said inspection drum, for reciprocating said blocking pad in a direction moving toward or away from said suction pad, wherein said movable carrier moves with said blocking pad toward said suction pad and causes said blocking pad and said suction pad to hold the filter cigarette therebetween.
 8. The inspection device according to claim 7, wherein: said movable carrier includes a cigarette holder having said receiving grooves.
 9. The inspection device according to claim 7, further including separating means for forcibly separating said blocking pad from the cigarette end of the filter cigarette after the filter cigarette passes said inspection position.
 10. The inspection device according to claim 9, wherein: said separating means includes a rod coupled to said blocking pad, a spring for urging said rod toward said suction pad, and a cam mechanism for moving said rod against an urging force of said spring in such a direction that said blocking pad is separated away from said suction pad. 